If it's not the wafer, what "new materials supplier" is there? Who's putting the gun to their head to change suppliers on this sole-sourced part. Logically, continue making it with the old material until the new material gets approved. Any quality/supply issues will cause big trouble for manufacturers dependent on it.

I'm skeptical. Mergers and acquisitions are never good for products. AD will surely consolidate fab, remove redundant teams, "improve" things to lower costs. Increasing shareholder value is paramount and great art is never about that.

Can be the steel in the metal can, can be the kovar for the leads, maybe it is the isolation standoff. None of which should effect the performance too much.Dont be afraid for the LTZ1000. I'm sure that Agilent and Linear signed a contract for the availability, which is a bounding contract for Keys. and Analog.Also, if they change something, they need time to verify it. This is not a digital gate, where you measure the rise time, and say that it is OK. Just making sure, that the drift for the first 2x1000 hours is OK: 3 months. With about 12 weeks extra as lead time.

Linear has a very different approach for the market. They make products, which sells in the 1000s and not the millions, and they have higher profit margin on it. Why sell microcontollers with billions of transistors in it, and have 5 cents of profit on each, when you can sell an opamp with a dollar of profit on it. The LT5400, which is "just" 4 resistor sells for almost the same as a Apple A8.

I am pretty sure (99%) the LTZ1000 won't go into obsolescence in near future.

Ever heard of the mil./space version of LTZ1000 with a price tag of US$1500 - might be DKK 1500 =US$ 300, pardon but I remember the number 1500 and not the sales channel, the number had me running in search for another source

What I do remember is the claim of "longe lead-time EOL sourcing", "One known fab only" (US as I remember), "narrowed wafer specs", "preconditioned" ...... and a documentation the size of the holy book

Any one ever thought of what it takes to produce and prove a product that stable that other people are willing to bet 10-11 digit US$ project on it ?If you "own" that product you won't "kill" it

I ordered a LTZ1000A 4 months ago directly from Linear's website.. still waiting.

Quoting myself to provide an update. I contacted Linear.. they said they'd be shipping me one today. So I guess my order just got forgotten somehow. Or they felt bad and are giving me one from a secret stash.

I have been noticing that some a very tiny percentage of the most recent LTZs have a lot of 1/f noise and popcorn noise. This is related to contamination of the junction layers with metals, (that are normally extracted during processing by infusion of phosphorous on the back side of the wafer, followed by a long bake at 900oC) and/or radioactive particle contamination. I suspect that something in the fab has gone Wr0nG, and they are trying to fix it. I wonder if this is related to the recent contamination in the atmosphere in the northern hemisphere with radioactive contaminants. Maybe it's time to coat the chip with super-pure silicone RTV before sealing the package?

I'm going to shoot a question at LTC and see if they will cough up the information...

...I have been noticing that some a very tiny percentage of the most recent LTZs have a lot of 1/f noise and popcorn noise. This is related to contamination of the junction layers with metals, (that are normally extracted during processing by infusion of phosphorous on the back side of the wafer, followed by a long bake at 900oC) and/or radioactive particle contamination. I suspect that something in the fab has gone Wr0nG, and they are trying to fix it. I wonder if this is related to the recent contamination in the atmosphere in the northern hemisphere with radioactive contaminants. Maybe it's time to coat the chip with super-pure silicone RTV before sealing the package?

I'm going to shoot a question at LTC and see if they will cough up the information...

-Ken

Radioactive contamination is not leading to popcorn noise. If at all one would get something like a few random errors in high densitiy DRAM of flash chips due to high energy alpha decay. Today most of those errors won't be visible due to chip internal error correction. So it is definitely not due to radioactive contamination.

The 1/f and popcorn noise is more due to chemical contamination's and maybe crystal defects. This might be hard to track, as it can be really trace amounts, both in the fab and in the wafers. Especially popcorn noise is something about a single defect (e.g. wrong atom) sitting at a sensitive place. More such defects at not so sensitive places give a source of 1/f noise.

Usually there is no way to get rid of trace contamination - it's all about starting clean and keep it clean. A common practice is removing some of the surface by etching to get rid of damages from cutting the wafers.

In the early days they has a story about yield being much lower after lunch. The anecdote is they got the yield back up, when they offered free lunch, as they traced the problem back to copper contamination from the money the workers used to pay the lunch.

I have been noticing that some a very tiny percentage of the most recent LTZs have a lot of 1/f noise and popcorn noise.

hello Ken,

can you expound on "a lot of noise", ie; some measurement details? how far off-spec or in-spec?

best regards.

I was asking this too.

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The data sheet specifies 1.2uVpp (typical) and 2.0uVpp (maximum) for 1/f noise (and, presumably, popcorn noise as well)-- some (a very few actually) recent parts are showing LF noise that is over the data sheet limit of 2.0uVpp. "Out Of Part Spec" [OOPS] == BAD PART. I'm assuming here that a proper circuit is used and a "draft excluder" (some kind of cap) is placed over the LTZ top and bottom-- and the part is still OOPS.

What is the source of "Some recent parts?"? How many are we talking about and what date codes?? Are these actual real parts from LT or authorized distributor? Was this on a known good PCB design?

Normally it is -very- rare to see a real LT factory checked LTZ out of spec on a properly built board, and we've seen about zero of what you're talking about on recent batches this year. I think over the several hundred I can count the bad LTZ's on one or two fingers, and LT replaced them since they came directly from LT (They will also do that if they come from a real authorized distributor, but not if you bought them from some broker or eBay, etc).

It is common to see the noise on these parts from the shady parts brokers / dealers trying to peddle the "floor sweeping" rejected / fake parts that somehow got legs and walked out of the fab, or sometimes someone got hold of some reject die and repackaged them. You can usually tell when the parts aren't sealed in the proper tray with the LT logo.

Those "used" LTZ parts on eBay are a bit suspect also - you never know what blowtorch was used to get the parts demounted. You might get lucky and they are fine, and maybe not.

noise testing is not cheap.So I guess that LT is only measuring wideband noise for a short time and not the 1/f noise in excess of 10 seconds during production.The closer you look the more noise you will find.I have also the impression that newer buried zeners (AD586/AD587) have more (popcorn) noise but I will have to verify this with older stock devices.

My LTZ#5 DC 0945 via official distributor has also a lot of popcorn noise in excess of 2uV.If you look at the "right" 10 seconds measurement duration you will see only the typical 1.2uVpp noise.

Andreas,...that's why the datasheet clearly states "about 1.2uV noise". 2uV p-p is listed as max, and that data looks still in the ballpark of that. You also have take your measurement uncertainty into account and look at how far your experiment drifts in the same time frame, as well as the overall noise floor of your setup. Are you scanning other known Vrefs simultaneously to compare? When you're down at uV levels that helps to distinguish noise on a -single- device from your experiment setup noise. The earlier part of your data is quieter for sure, did something get switched on nearby?

I would expect the LTZ1000 to be tested for a little longer than 10 seconds. It already needs some time to get a stable temperature - so no way to do a super fast test anyway. Popcorn noise is likely one of the more important reasons to do the checks and sort out failing units.

However with popcorn noise is can be difficult to detect - especially that type of noise with more infrequent jumps. Chances are one would not notice this in a short interval of maybe 30 seconds. Those very low frequency popcorn cases are the really bad ones, as one never knows and longer averaging also does not help that much. With the more frequent and symmetric jumps, like in TIN's jummpy sample from Ebay one has in theory the chance to detect and even correct for this.

I would expect the LTZ1000 to be tested for a little longer than 10 seconds. It already needs some time to get a stable temperature - so no way to do a super fast test anyway. Popcorn noise is likely one of the more important reasons to do the checks and sort out failing units.

However with popcorn noise is can be difficult to detect - especially that type of noise with more infrequent jumps. Chances are one would not notice this in a short interval of maybe 30 seconds. Those very low frequency popcorn cases are the really bad ones, as one never knows and longer averaging also does not help that much. With the more frequent and symmetric jumps, like in TIN's jummpy sample from Ebay one has in theory the chance to detect and even correct for this.

hello,

looks like the biggest bottleneck in the production of LTZ1000 would be effective noise testing.

I still fail to see the big LTZ datasheet spec "Oops" in Andreas' data. That shows a part still within the realm of datasheet specs it looks to me: It's showing clearly a P-P value of ~2uV (equipment / experiment noise -floor- limits are not known) which is the datasheet value. Of course the longer you measure, the more likely you'll see more noise. Especially as 1/f creeps in. Double the measure time and you get another octave's worth of 1/f possibilities. If there is -some- popcorn noise, it will probably still be able to pass the LT quality check.

The problem we saw before on just one or two parts was an excursion more like 6 or 8uV P-P across 10 sec - clearly out of spec. Those got replaced.

DigilentMinds: Were you thinking about a bigger "oops" deviation from datasheet value? That's what I was curious about. How many parts and what date codes are we talking about??